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<br />Step 1. Compute the overland flow trrrvel tj~e. <br />Reach A to B (forest COVEr). From Fig. 4.4.1.4-1 for a <br />slope of 7%, read V - 0.7 ft!sec. <br /> <br />_ length <br />Tt velocit.y <br /> <br />500 ft <br />0:7 ft/'~ec. <br /> <br />- 714 see <br /> <br />Reach B to C (street gutter)" From Fig, 4.4.1.4-1 for a <br />slope of 2~, read v = 2.8 ft/sec. <br /> <br />Tt - <br /> <br />length <br />velocity <br /> <br />900 ft _ <br />2.8h.lsec - 321 see <br /> <br />Step 2. Compute the storm drain flow travel. time. <br />Reach C to D. Use Manning's equaU,on to compute pipe-full <br />velocity. <br /> <br />1.49 D 2/3 1/2 <br />v - -n('4) s <br />1.49 3 2/3 1(2 <br />v - 0.015('4) (0.0l.5) <br /> <br />10 ft/sec <br /> <br />Tt - <br /> <br />length _ _ ~JO f~, <br />velocity 10 ft/sec <br /> <br />.- 200 se" <br /> <br />Step 3. Compute the open channel flo'," travE!l time. <br />Reach D to E. Use Manning's equat:.on to compute bank-full <br />velocity. <br /> <br />v _ 1.49 r2/3 sl/2 <br />n <br /> <br />n - 0.019 for gunit" channel <br /> <br />s - <br /> <br />0.005 <br /> <br />v - <br /> <br />1.49 (1.78)2/3 (0.005)1/2 _ 8.2 ft/sec <br />0.019 <br /> <br />Tt <br /> <br />length _ <br />velocity <br /> <br />_ --2, OOO_i.!'-. _ 366 see <br />8.2 ft/sec <br /> <br />~ <br /> <br />LCS-I<.'M Manual <br /> <br />'< .4--'-16 <br /> <br />April 1979 <br />